Step 1: Digging a Cellar On land, a majority of wells begin with digging a cellar from three to fifteen feet in depth. The purpose of a cellar is to align the production Christmas tree at ground level, providing easier access to the valves, chokes, and other equipment.

Step 2: Running a Conductor Pipe The first string of pipe used in a well is called the conductor pipe, or drive pipe. The pipe is usually 30-36 inches in diameter. A large diameter hole is drilled to a specified depth, usually one or two hundred feet, and the pipe is driven into the ground..

Step 3: Connecting the BOP An adapter flange, or drilling flange, is welded to the conductor pipe to connect a diverter system or a blowout preventer system to control wellhead pressure.

Step 4: Running the Surface Pipe A hole is drilled for the well’s first string of pipe, the surface pipe, and the pipe is run in the hole. There may be several strings of pipe in a well, each run to a different depth. The number of strings is determined by the number of zones being drilled through. These can include fresh water, salt water, and potential production zones. Each zone is isolated, or cased off, until it is to be produced. .

Step 5: Connecting the Surface Pipe The surface pipe is cemented in place back to the surface. This holds the pipe in place and seals off the zone. A cement plug is left in the pipe so that the BOP system may be disconnected safely. The BOP is then removed from the adapter flange.

Step 6: Cutting the Conductor Pipe and Surface Casing The surface pipe is drained, the adapter flange (or drilling flange) is cut off, and both the conductor pipe and the surface casing are cut to the proper height to allow the top of the completed wellhead to be at ground level.

Step 7: Installing the Casing Head Housing and Base Plate The casing head housing is welded in place on the inside diameter and the outside diameter of the surface casing. The housing is then tested to assure there are no leak paths in the welds.

Step 8: Installing the BOP System The BOP system is installed above the casing head housing and then tested. To test the BOP system, the test plug is made up on the drill string and lowered through the BOP system onto the casing head bowl. Pressure is applied from above the plug to test the BOP system.

Step 9: Installing the Casing Head Wear Bushing A wear bushing is installed to protect the interior of the casing head from damage by drilling equipment.

Step 10: Installing the Intermediate String A hole is drilled for the intermediate string and the casing is run in the hole and cemented in place. A cement plug is left in the intermediate casing, just as it was in the surface casing. .

Step 11: Installing the Casing Hanger and Casing Spool The intermediate casing is suspended from the block above the rig floor, the BOP is picked up, and the casing hanger is installed on top of the casing head. Holes are cut in the casing to allow the drilling fluids to drain out of the casing riser. When the fluid has drained, the casing is cut off to the appropriate height and the casing spool is installed.

Step 12: Installing the BOP System The BOP system is installed above the casing spool and then tested. To test the BOP system, the test plug is made up on the drill string and lowered through the BOP system onto the casing head bowl. Pressure is applied from above the plug to test the BOP system.

Step 13: Installing the Wear Bushing The wear bushing running tool is made up on the drill string and the wear bushing installed on the running tool. The wear bushing is then lowered through the BOP system, until it rests in the casing spool bowl, then is locked into place. The running tool is removed and drilling resumes.

Step 14: Running the Production Casing String The production casing string is usually run to the total depth of the well. A hole is drilled for the production casing and the casing is run in the hole and cemented into place. A cement plug is left in the production casing, as in the previous steps.

Step 15: Installing the Casing Hanger and Tubing Spool The production casing is suspended from the elevators at the rig floor, the BOP is picked up, and the production casing hanger is installed in the same way as the previous casing hanger. The tubing spool is installed in the same way as the casing spool. After the spool has been installed, the seals and connections are tested, and the BOP system is reinstalled..

Step 16: Running the Production Tubing The production tubing is installed inside the production casing. Unlike casing, the production tubing is not cemented in the well so it may be removed later, if necessary.

Step 17: Installing the Down hole Packer Assembly A down hole packer assembly (a type of seal assembly) is run and installed in the production casing to seal the reservoir from all strings of pipe, except the production tubing.

Step 18: Installing the Tubing Hanger The tubing hanger is installed on the tubing at the rig floor, then lowered into the bowl of the tubing spool. The packer seals are tested, and a backpressure valve is installed in the tubing hanger so that the BOP can be removed safely. After the valve has been installed the BOP is removed. .

Step 19: Installing the Christmas Tree The production Christmas tree, sometimes called the flow assembly, controls the flow of the well. It is made up of a seal flange, or tubing head adapter, a series of valves, and a choke. The valves are stacked vertically and horizontally to provide backup should a valve fail. Each Christmas tree has at least one actuated surface safety valve to shut down the well in an emergency and prevent damage to equipment downstream. The Christmas tree is connected to a flowline, which transports the well’s fluid or gas. The Christmas tree is oriented properly, picked up, lowered over the neck of the tubing hanger, and connected to the tubing spool. The connections and seals are tested, and the well is now ready for production testing.